大学教育に適用可能な マイクロスケール物理化学実験

Development of microscale experiments in physical chemistry for chemical education

for undergraduates

Kenji Katayama, Shota Kuwahara,

Naomi Tsuchiya, Ryo Horie

Chuo University

2013/3/22 日本化学会第93春季年会

Outline

1. Introduction

1-1. Microscale experiments for university

1-2. Typical curriculum of Physical Chemistry

2. Development of microscale experiments

2-1. Gas law

2-2. Calorimetry

2-3. Phase diagram

2-4. Chemical equilibrium

2-5. Electromotive force

3. Conclusion

Microscale experiment

Neutralization titration

New chemical education using small equipments

Electrolysis Gas explosion

Grey, Egerton C (1928). Practical Chemistry by Micro-Methods.

El-Marsafy, M K (1989). "Microscale Chemistry Experimentation" Thompson, S. "Small-Scale Chemistry". National Small-Scale Chemistry Centre. Colorado State University.

By Prof. Ogino (Japan) Environment friendly Risk reduction

Short experiment time Improvement of understanding

Cheap cost Attract interest

2010/ 6/14 @ Chuo Univ.

Problems for professional experiments • Expensive equipment • Contents oriented depending on university

Microscale experiments for university

Environment friendly Risk reduction Short experiment time Improvement of understanding Cheap cost Attract interest

Microscale experiments for non-chemists

Budget: >10 timese Mechanical and analytical equipment can be utilized

Mathematical calculations can be made by computers

Microscale experiments for chemists

• To develop microscale experiments in physical chemistry • Curriculum based experiments • Low cost

Selection

of subject

Planning &

Development

Check Trial experiment Verification

Scheme of experiment development

Typical curriculum of Physical Chemistry

1. Property of gas

2. Enthalpy

3. Entropy

4. Mixture of chemicals

5. Phase diagram

6. Equilibrium

7. Electrochemistry

1. Property of gas

2. Enthalpy

3. Entropy

4. Mixture of chemicals

5. Phase diagram

6. Equilibrium

7. Electrochemistry

Work done by gas

Calorimetry

Liquid-liquid equilibrium

Electromotive force of electrochemical cells

Z. Szafran, R. M. Pike, J. C. Foster, “Microscale General Chemistry Laboratory”, Wiley.

東海林恵子、荻野和子, 化学と教育 49 712 (2001) .

Typical curriculum of Physical Chemistry

Reaction equilibrium and temperature dependence

Freezing point depression

Microscale experiment 1 – Work done by gas

Aim

1. Experience the Boyle’s law.

2. Understand of isothermal compression adiabatic compression

Physical Chemistry, Atkins, sixth edition

Syringe

Z stage

Work done by gas – Setup–

AD board Temperature monitoring

Equipment

Pressure gauge

Plastic syringe

Temperature sensor

Cock 1. Simple experiment 2. Easy handling 3. Direct monitoring of pressure and temperature

Compressed

dz

2

1

V

Vin PdVw

F

V

P

PdVAdzPdzFdwin

Work done by gas – Principle –

Adiabatic ⇒ Press the syringe Quick

Isothermal ⇒ Press the syringe Slowly (Temperature constant)

Work done by gas – Isothermal and adiabatic compression –

Work done by gas – Result for Isothermal compression–

PV curve

Calculated work

Work (Theoretical)

Work done by gas – Result for Adiabatic compression–

Temperature change

Temperature (Theoretical)

Microscale experiment 2 – Calorimetry

Aim

1. How to measure enthalpy.

2. To understand neutralization heat

of acid and base reaction

SHIMADZU

Commercial equipment

3. To consider the relation between DHhyd by and ion radius

Calorimetry – Setup–

100 mL

Conventional

17

5 cm 15 cm

12 cm

10 mL bottle

Z. Szafran, R.M.Pike, J.C.Foster, MICROSCALE GENERAL CHEMISRY LABORATORY, Wiley (1993)

Microscale

1. Small heat capacity of container 2. Small amount of reagents 3. Small working place

Calorimetry – Neutralization of acid and base–

20

22

24

26

28

0 60 120 180 240Time[s]

Tem

pera

ture

[℃]

⊿T

TCTmCH containerp DDD

Temperature change after HCl and NaOH mixing

molkJH /4.66⊿

molkJH ltheoretica /5.56⊿

19

M+(g)+X-(g)

MX(s)

ΔHHyd

M+(aq)+X-(aq)

ΔHL

Theoretical

ΔHSol

Experimental 10

14

18

22

26

0 100 200 300Time[s]

Tem

pe

ratu

re[℃

]

KI

NaI

KCl

NaCl

⊿Hexperimental

18.9kJ/mol

17.9kJ/mol

-7.1kJ/mol

1.79kJ/mol

⊿Htheoretical

20.3kJ/mol

17.2kJ/mol

-7.5kJ/mol

3.9kJ/mol

KI

KCl

NaI

NaCl

KI KCl NaI NaCl

-630 -699 -712 -785

Hydration enthalpy

Ion radius

Bigger Smaller

Calorimetry – Neutralization of various ions –

Microscale experiment 4 – Binary phase diagram

Aim

1. How to make and use binary phase diagram.

2. To understant the phase rule of liquid-liquid equilibrim.

Conventional

Binary phase diagram – Setup–

21

Microscale Conventional

Thermometer

Screw bottle x 6 (1 mL)

Hot magnetic stirrer

1. Small working place 2. Short experimental time 3. Easy comparison for different

ratio samples

Binary phase diagram – Methanol / Cyclohexane phase change–

Heating

Cooling

P = 2 Two phase

P = 1 Single phase

Record the temperature of cloud points

Binary phase diagram – Result of phase diagram–

The error of the temperature is within 1 OC.

H. Matsuda et al., J. Chem. Eng. Data 43 184 (2003).

Binary phase diagram – Further experiment, Lever rule–

b

a

（nA, nB：the mass of each phase） bBaA lnln

The lever rule

Binary phase diagram – Further experiment, Lever rule–

b

a

Mass fraction [-]

Phase a Phase b

The lever rule 0.23 0.77

Experimental

Methanol mass fraction [-]

The lever rule 0.64 Experimental

b

a

Mass fraction [-]

Phase a Phase b

The lever rule 0.23 0.77

Experimental 0.26 0.74

Methanol mass fraction [-]

The lever rule 0.64 Experimental

Mass fraction of methanol (a) = r(a) x V(a)

Mass fraction of methanol (b) = r(b) x V(b)

V(a)

V(b)

Binary phase diagram – Further experiment, Lever rule–

b

a

Mass fraction [-]

Phase a Phase b

The lever rule 0.23 0.77

Experimental 0.26 0.74

Methanol mass fraction [-]

The lever rule 0.64 Experimental 0.65

0.74

0.76

0.78

0.8

0.82

0.84

0.86

1.34 1.345 1.35 1.355

Re

fla

cti

ve

in

de

x

Mass fraction of methanol [-]

Refractrometer

Binary phase diagram – Further experiment, Lever rule–

Microscale experiment 5 – Chemical equilibrium

Aim

1. To understand the property of Keq

2. To confirm the temperature dependence of Keq.

(Van’t Hoff eq.)

Conventional

Chemical equilibrium– Setup–

29

Microscale

光源

平板ヒーター

試料セル

分光器

Spectrometer

Light source

Sample

Rubber heater

Sample arrangement

1. Small working place 2. Direct mixing in an optical cell Small amount of reagents

3. Open-field spectrometer Easy temperature control

Chemical equilibrium– Reaction–

23 )(SCNFeSCNFe 　

Color change for different concentrations

Chemical equilibrium – Keq dependence on concentration–

# Abs [-] Keq

Sample 1 1.0 0.98 0.13 0.87 0.87

Sample 2 0.80 0.65 0.090 0.71 0.91

Sample 3 0.60 0.43 0.060 0.54 0.94

Sample 4 0.40 0.27 0.040 0.36 0.96

Sample 5 0.20 0.15 0.020 0.18 0.98

To confirm Keq does not depend on the concentration.

Chemical equilibrium – Confimation of Van’t Hoff equation–

To confirm Van’t Hoff equation.

R

H

T1d

Klnd r

D

y = -1.7E+03x + 0.60 -5.2

-5.1

-5

-4.9

-4.8

-4.7

-4.6

-4.5

0.0031 0.0032 0.0033 0.0034 0.0035

-ln

K

1/T

mol/kJ14rH Δ

Microscale experiment 6 – Electromotive force

Aim

1. To understand electromotive force (EF) and Nernst’s equation.

2. To calculate DG, DS, DH by the temperature dependence of EF.

Conventional

Electromotive force– Setup–

Microscale Conventional

12.5 cm

8 cm

Diameter 2.2 cm

東海林恵子, 荻野和子, 化学と教育, 49, 712, (2001) 1. Easy comparison for different

concentratins 2. Easy measurement of temperature

dependence. 3. Small amount of reagents

Chemical equilibrium – Nernst’s equation–

Confirmation of electromotive force for different concentrations

][

][ln

2

2

Cu

Zn

nF

RTEE

y = -0.0098x + 0.9496

0.8

0.9

1

1.1

-8 -6 -4 -2 0 2 4 6 8ln[Zn2+]/[Cu2+][-]

Ele

ctr

o m

otive fo

rce[V

]

y = -0.0142x + 1.3434

0.7

0.8

0.9

1

25 30 35 40 45 50Temperature[℃]

Ele

ctr

o m

otive

fo

rce

[V

]

Chemical equilibrium – Thermodynamic calculations–

Thermodynamic energies calculated.

nFEG D

ST

G

p

D

D

D

STGH DDD

V99.0E D

mol/kJ8.190G D

molK/J6.2740S ・D

mol/kJ5.1007H D

Conclusion

We succeeded in developing the microscale experiments in physical chemistry for chemical education of undergraduate students.

Series of experiments based on the curriculum Low cost Educational

Web of microscale experiment http://www.chem.chuo-u.ac.jp/~spec/microscale_pre.html

Acknowledgement

This experiments were introduced in the physical chemistry experiments for chemistry students since 2012.